Is the soybean healthy or not? Should you eat soy? Most doctors agree that fermented soy products are healthy, such as tempeh, miso, tamari, natto, and soy yogurt, but what about other soy products, such as soybeans, soy milk, tofu, and edamame? The answer is both simple and complicated. Most soy products can have great health benefits, but soybeans are one of the most genetically modified crops, along with corn and cotton. 90% in fact! So, it goes without saying (but I will in another blog) that we should avoid all GMO foods.
So, unless you’re allergic to soy, you can eat any non-GMO, organic, fermented soy product and not worry about any health risks. That statement is pretty much agreed upon by all sides of the controversy. The enzymes and probiotics from fermented soy make foods like miso a superfood.
Okay, but what about soy products that have not been fermented? Are they helpful or harmful? Soy contains phytoestrogen. It actually acts naturally to either compete with our own estrogens or enhance them, both in a healthy way. How can it do both? It turns out that we have two types of estrogen receptors in our bodies, alpha and beta (1).
Drug estrogens cannot selectively bind with alpha or beta like soy phytoestrogens can, so they cause health risks that soy does not. For example, estrogen pills negatively impact the liver and the uterus, because those organs are aided by alpha receptors. Soy actually protects the liver and uterus and also improves menopausal symptoms (1).
Now, bones have beta estrogen receptors. Guess what? Soy protects bones as well by increasing bone mineral density. It even prevents bone loss over time. It does this better than progesterone cream, one study shows. In fact, one serving of soy per day significantly lowers the risk of bone fracture. That’s just 5-7 grams of soy protein or one cup of soy milk. However, I would recommend a whole, soy food instead, preferably fermented (1).
Soy milk often contains refined sugar, carrageenan, and other harmful thickeners. I prefer nut milk that is unsweetened and carrageenan-free. Even better, make your own raw nut milk. Joann will show you how to do that in another recipe blog. Let me know in the comments what your favorite plant-based milk is.
Soybean and the Thyroid
Can soy suppress thyroid function? It does have goitrogenic compounds, but so do broccoli and flax seeds. The only reason it may hinder thyroid function is if your iodine intake is too low. If you get enough iodine, you will have no problem with soy, broccoli, or flax seeds (2). Take a healthy iodine supplement or put seaweed in your soup or salad. There are smaller amounts of iodine in green beans, zucchini, kale, spring greens, watercress, and strawberries. Organic kelp flakes are a good substitution for salt and will supply iodine as well.
Recommended Soybean Intake
So, how much soy is too much? Studies show that 7-18 servings neutralize some of the benefits of avoiding animal protein. Women who eat lots of soy have a lower chance of getting breast cancer and a better chance of surviving breast cancer than those who don’t, but how much should we limit it? A two-year study found no negative effects with two servings of soy products a day, whether it was tofu, soy milk, or soy protein (3). A Japanese study found that three servings were fine (4). Dr. Michael Greger recommends limiting soy products to no more than 3-5 servings per day (5).
What’s the takeaway here? Is the soybean healthy or not? Soy, like most other foods, can be corrupted. It gets an undeserved bad rep because it’s mostly GMO and its milk has taken sales away from cow’s milk. Unbiased studies, however, show that organic, non-GMO soy can be eaten daily, but no more than five servings, to protect against cancer and bone loss. Soy also protects the heart with its omega-3 fatty acids. It contains B vitamins, iron, zinc, and antioxidants as well. Take an iodine supplement, if needed, so that it doesn’t affect your thyroid.
Also, keep in mind that most of the GMO soy is fed to livestock, but I would still read labels to determine if the soy is non-GMO and organic. Obviously, if you are allergic to soy, avoid it, but it is a very healthy choice, especially if it has been fermented. We have a free mini course on fermenting foods to heal your gut. If you’re interested, see the graphic below to learn more. Also, please subscribe to our email newsletter to get more health tips. Thanks for visiting!
- Michael Greger M.D. FACLM. “Who Shouldn’t Eat Soy?” NutritionFacts.org. November 25, 2016, Volume 33.
- Michael Greger M.D. FACLM. “Can soy suppress thyroid function?” NutritionFacts.org. November 8, 2012.
- Gertraud Maskarinec, et. al. “Insulin-like growth factor-1 and binding protein-3 in a 2-year soya intervention among premenopausal women.” British Journal of Nutrition. Volume 94, Issue 3, September 2005, pp. 362-367.
- Nagata C., et. al. “Dietary soy and fats in relation to serum insulin-like growth factor-1 and insulin-like growth factor-binding protein-3 levels in premenopausal Japanese women.” Nutr Cancer. 2003; 45(2):185-9.
- Michael Greger M.D. FACLM. “How Much Soy Is Too Much?” NutritionFacts.org. February 19, 2013.
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